1. Field
Embodiments of the present invention relate to a throttle control system. More specifically, examples of the invention relate to a throttle control system favorably employed, for instance, in a throttle-by-wire system. The system can prevent a valve gear connected to a throttle valve from colliding with a full-close stopper in the driving of the throttle valve in a closing direction.
2. Description of the Related Art
A conventional throttle control system for a throttle-by-wire (TBW) system detects the operation angle of a throttle grip, and controls the opening and closing of a throttle valve by driving a drive motor of the throttle valve in accordance with the operation opening degree.
In the throttle control by TBW, when the throttle valve is moved from a near fully or fully opened position to a fully closed position, the throttle valve sometimes collides at a high speed with a stopper that limits the fully closed position of the throttle valve. Against this problem, Japanese Patent Application Publication No. Hei 8-74639 (JP '639) describes a throttle control system configured as follows to avoid the throttle valve from colliding with the full-close stopper. Specifically, JP '639 discusses a throttle control system that gradually decreases a fully-closed limiter position toward a fully closed position when an actual opening degree of the throttle valve exceeds a predetermined opening degree in a fully closing direction. The predetermined opening degree being slightly shifted in an opening direction from the fully closed position.
The throttle control system described in JP '639 is to avoid the throttle valve from colliding with the stopper. However, since the throttle control system is designed to gradually move the fully-closed limiter position toward the fully closed position, the moving speed of the throttle valve does not change. For this reason, when the throttle valve is operated in a rapidly closing manner by a throttle operating device, the movement of the fully-closed limiter position may sometimes fail to follow the rapid closing operation on the throttle valve.